Optical inspection methods

ABSTRACT

Inspection methods. A method includes adhering an optical blocking layer directly onto and in direct mechanical contact with a semiconductor process wafer, the blocking layer being substantially opaque to a range of wavelengths of light; applying at least one layer over the blocking layer; and inspecting optically at least one wavelength at least one inspection area, the blocking layer extending substantially throughout the inspection area. An inspection method including adhering an optical absorbing layer to a semiconductor process wafer, where the absorbing layer is configured to substantially absorb a range of wavelengths of light; applying at least one layer over the absorbing layer; and inspecting optically at least one wavelength at least one inspection area of the process wafer. A manufacturing method including ascertaining if a defect is present within a photoresist layer, and changing a semiconductor manufacturing process to prevent the defect, if the defect is present.

This application is a continuation application claiming priority to Ser.No. 11/872,900, filed Oct. 16, 2007.

FIELD OF THE INVENTION

The invention generally relates to methods for optical inspection ofsubstrates.

BACKGROUND OF THE INVENTION

The ability of optical inspection tools to provide high-value resultsmay be a strong function of their ability to filter the inspection layerof interest from underlying prior level patterns that are not ofinterest. In post-lithography inspections, using techniques such asprocess window qualifications (PWQ), wafers may be inspected at thelithography step with multiple process conditions. Test macros forroutine inspections may be generally performed on flat bare siliconmonitors to simulate a production process. There are difficulties inroutine inspections with product wafers that contain multiple filmstacks, primarily due to interference from underlying films, andunderlying film topography. This is particularly an issue in the backend of line (BEOL), where lithography focus budgets erode relative tointra-die topography. There exists a need for a method for inspectingreal product substrates with topography that may influence scanner focuscontrol in very non-obvious manners, in order to accurately assess theprocess center.

SUMMARY OF THE INVENTION

The present invention relates to an inspection method, said methodcomprising:

adhering an optical blocking layer directly onto and in directmechanical contact with a semiconductor process wafer, said opticalblocking layer being substantially opaque to a range of wavelengths oflight;

applying at least one layer over said optical blocking layer, wherein afirst layer of said at least one layer is adhered directly onto saidoptical blocking layer; and

inspecting optically at least one wavelength within said range ofwavelengths at least one inspection area of said at least one layer,said optical blocking layer extending substantially throughout saidinspection area.

The present invention relates to a process wafer optical inspectionmethod, said method comprising:

adhering an optical absorbing layer to a semiconductor process wafer,said optical absorbing layer configured to substantially absorb a rangeof wavelengths of light;

applying at least one layer over said optical absorbing layer, wherein afirst layer of said at least one layer is adhered directly onto saidoptical absorbing layer; and

inspecting optically at least one wavelength within said range ofwavelengths at least one inspection area of said process wafer havingsaid optical absorbing layer, said optical absorbing layer extendingsubstantially throughout said inspection area.

The present invention relates to a manufacturing method, comprising:

providing an integrated semiconductor wafer having an optical blockinglayer, said blocking layer configured to block a range of wavelengths oflight;

adhering a photoresist layer to said wafer having said blocking layer,wherein said adhering has resulted from a semiconductor manufacturingprocess.

inspecting optically at least one wavelength within said range ofwavelengths at least one inspection area of said photoresist layer, saidoptical blocking layer extending substantially throughout saidinspection area;

based on said inspecting, ascertaining if a defect is present withinsaid photoresist layer; and

changing said semiconductor manufacturing process to prevent saiddefect, if said defect is present within said photoresist layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention are set forth in the appended claims. Theinvention itself, however, will be best understood by reference to thefollowing detailed description of illustrative embodiments when read inconjunction with the accompanying drawings.

FIG. 1A is an illustration of a cross-section of a substrate having anoptical blocking layer, in accordance with embodiments of the presentinvention.

FIG. 1B is an illustration of the substrate and layers of FIG. 1A afterpatternwise imaging and developing a radiation sensitive resist layer,in accordance with embodiments of the present invention.

FIG. 1C is an illustration of the substrate and layers of FIG. 1B afterthe radiation sensitive resist layer and ARC layer have been strippedaway, and a via has been etched into the substrate, in accordance withembodiments of the present invention.

FIG. 1D is an illustration of the substrate and layers of FIG. 1C afteradditional layer deposition and processing, in accordance withembodiments of the present invention.

FIG. 1E is an illustration of the substrate in FIG. 1D, after etching atrench and stripping away the radiation sensitive resist layer, theantireflective coating, the low temperature oxide coating, and theorganic interlayer planarizing layer, in accordance with embodiments ofthe present invention.

FIG. 1F is an illustration of the substrate in FIG. 1E after removal ofthe optical blocking layer and hard mask layer, in accordance withembodiments of the present invention.

FIG. 2 is a flow chart of steps in an inspection method utilizing anoptical blocking layer, in accordance with embodiments of the presentinvention.

FIG. 3 is a flow chart of steps in an inspection method utilizing anoptical absorbing layer, in accordance with embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Although certain embodiments of the present invention will be shown anddescribed in detail, it should be understood that various changes andmodifications may be made without departing from the scope of theappended claims. The scope of the present invention will in no way belimited to the number of constituting components, the materials thereof,the shapes thereof, the relative arrangement thereof, etc., and aredisclosed simply as examples of embodiments. The features and advantagesof the present invention are illustrated in detail in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout the drawings. Although the drawings are intended toillustrate the present invention, the drawings are not necessarily drawnto scale.

The present invention relates to optical blocking and absorbing layerswhich may be inserted into a manufacturing process flow for asemiconductor wafer to enable optical inspection, such as brightfieldinspection, where the optical blocking and absorbing layers may be tunedfor an inspection wavelength of interest. An optical blocking layer maybe substantially opaque to a range of wavelengths of light, which mayinclude the inspection wavelength of interest. An optical absorbinglayer may be configured to substantially absorb a range of wavelengthsof light, which may include the inspection wavelength of interest.

The optical blocking and absorbing layers may be adhered to a substratein such a fashion that the optical blocking and absorbing layers may bedisposed beneath film stacks that may be etched or modified, thusenabling defect source partitioning between processing steps such aspost hardmask deposition, post Via lithography, post Via reactive ionetching (RIE), post interlayer planarizing film coating/cure, post lowtemperature oxide (LTO) deposition, and post trench lithography and RIE.Such optical blocking and absorbing layers may be configured to reflectand/or absorb optical inspection wavelengths that may otherwisepenetrate a film stack, of material deposited in a semiconductormanufacturing process, thus preventing the collection of inspectioninformation from underlying layers that may not be of interest. Withoutthe use of such optical blocking and absorbing layers, the inspectionsignal from these underlying layers may increase and the signal-to-noiseratio to detect the layer of interest may decrease, where the ratio mayreach a level which may render the inspection worthless.

FIG. 1A is an illustration of a cross-section of a substrate 100 havingan optical blocking layer 105 adhered directly onto and in directmechanical contact with the substrate 100. The substrate 100 may includea semiconducting material, an insulating material, a conductive materialor any combination thereof, including multilayered structures. Thus, forexample, substrate 100 may be a semiconducting material such as Si,SiGe, SiGeC, SiC, GaAs, InAs, InP and other III/V or II/VI compoundsemiconductors. The substrate 100 may be, for example, a process wafersuch as that produced in various steps of a semiconductor manufacturingprocess, such as an integrated semiconductor wafer. The substrate 100may comprise more than one layer, such as layer 101 and layer 102 inFIG. 1A. The substrate 100 may be a layered substrate such as, forexample, Si/SiGe, Si/SiC, silicon-on-insulators (SOIs) or silicongermanium-on-insulators (SGOIs). The substrate may comprise layers suchas a dielectric layer, a barrier layer for copper such as SiC, a metallayer such as copper, a silicon layer, a silicon oxide layer, the like,or combinations thereof. The substrate 100 may comprise an insulatingmaterial such as an organic insulator, an inorganic insulator or acombination thereof including multilayers. The substrate 100 maycomprise a conductive material, for example, polycrystalline silicon(polySi), an elemental metal, alloys of elemental metals, a metalsilicide, a metal nitride, or combinations thereof, includingmultilayers.

In some embodiments, the substrate 100 may include a combination of asemiconducting material and an insulating material, a combination of asemiconducting material and a conductive material or a combination of asemiconducting material, an insulating material and a conductivematerial. An example of a substrate that includes a combination of theabove is an interconnect structure.

The optical blocking layer 105 may be substantially optically opaque toa range of wavelengths of light, and may comprise materials such astantalum nitride, tungsten nitride, gallium nitride, titanium nitride,tantalum, titanium, hafnium oxide, or combinations thereof. The opticalblocking layer may be applied to the substrate through processes such assputtering, chemical vapor deposition (CVD), plasma enhanced chemicalvapor deposition (PECVD), spin-coating, etc.

The optical blocking layer may be configured such that the maximumpossible fraction of light may be reflected off the optical blockinglayer, and that light which does enter the optical blocking layer isquickly attenuated. Thus, light passing through only inspection layersof interest may reflect back to the detector of an inspection device,restricting the optical inspection data to the layers of interest, wherethe optical inspection data may be used in die-to-die or within-diearray comparisons between a test sample and an accepted standardspecimen having no defects.

The film may be sufficiently thin such that it exhibits a highlyconformal mapping of the existing substrate topography and may preservesubstrate topography while blocking signals from lower layers embeddedwithin the substrate topography. For example, the optical blocking layermay have a thickness in a range from about 25 angstroms to about 500angstroms, such as from about 25 angstroms to about 100 angstroms.

At least one layer 110 may be applied over the optical blocking layer105, where a first layer 112 of the at least one layer 110 may beapplied directly onto the optical blocking layer 105, and subsequentlayers may be applied on top of the first layer 110 in succession.

The at least one layer 110 may comprise a hard mask layer, anantireflective coating such as BARC, a radiation sensitive resist layersuch as a photoresist layer, an oxide layer, a metal layer, a metaloxide layer, a nitride layer, a dielectric layer, the like, orcombinations thereof. For example, in FIG. 1, the at least one layer 110may comprise a hard mask layer 112, an ARC layer 115, and a radiationsensitive resist layer 120.

The hard mask layer 112 may comprise a dielectric layer such as acarbon-doped oxide dielectric comprised of Si, C, O, and H (SiCOH), alow dielectric etch stop/barrier layer containing Si, C, and H such asBLOK and Nitrogen rich BLOK (NBLOK), tetraethylorthosilicate (TEOS), anitride layer such as a high density plasma (HDP) nitride layer, orcombinations thereof.

At least one inspection area of the at least one layer, such as a hardmask layer 112, may be inspected optically at least one wavelengthwithin the range of wavelengths to which the optical blocking layer 105is optically opaque. The inspection area may have topographicalvariation, such as trenches and vias for example, which may be presentfrom previous processing of the substrate or may be created insubsequent processing after which optical inspection may be performed.The optical blocking layer may extend substantially throughout theinspection area. The optical blocking layer may reflect opticalinspection wavelengths, block or prevent inspection wavelengthpenetration to lower layers of the substrate 100, and prevent collectionof information from underlying layers which may not be of interest. Theoptical inspection may be performed as each subsequent layer is adheredto the layer stack or when layers are modified by the manufacturingprocess (such as etching, exposure, or developing), thus allowing forthe inspection of each layer as it is applied and processed, and for theidentification of any defects which may be present in the appliedlayers.

FIG. 1B is an illustration of the substrate 100 and layers of FIG. 1Aafter patternwise imaging and developing a radiation sensitive resistlayer 120. The radiation sensitive resist 120 layer may be patternwiseimaged through a mask, exposing at least one region of the radiationsensitive resist layer 120 to radiation, resulting in production of anacid catalyst in the exposed at least one region of the radiationsensitive resist layer 120. The exposed region may be developed,resulting in the removal of regions 125 of the radiation sensitiveresist layer 120, wherein a relief pattern from the radiation sensitiveresist layer 120 may remain following the removal. The radiationsensitive resist layer 120 having the relief pattern may be opticallyinspected as described above, wherein the optical blocking layer 105 mayreflect and/or attenuate the wavelength of light used in the opticalinspection.

FIG. 1C is an illustration of the substrate 100 and layers of FIG. 1Bafter the radiation sensitive resist layer 120 and ARC layer 115 havebeen stripped away, and a via 130 has been etched into the substrate100, such as with an etching process, such as a plasma for example. Theoptical blocking layer 105 may be utilized to optically inspect the hardmask layer 112 and the via 130 as described above, where such aninspection may identify a defect in the hard mask layer 112 or theconfiguration of the via 130, which may have been caused by an etchingstep in a semiconductor manufacturing process, for example.

FIG. 1D is an illustration of the substrate 100 and layers of FIG. 1Cafter additional layer deposition and processing where additional layershave been adhered over the optical blocking layer 105. As illustrated inFIG. 1D, additional layers may be adhered over the substrate 100 havingan optical blocking layer 105, such as an organic interlayer planarizinglayer 135, a low temperature oxide layer 140, an antireflective coating145, and a radiation sensitive resist layer 150, for example. As eachadditional layer is adhered to the substrate 100, the layers may beoptically inspected for defects using the optical blocking layer 105 toreflect and/or attenuate the optical inspection wavelengths, thuspreventing penetration to lower layers of the substrate 100 andcollecting information from underlying layers that are not of interest.For example, the organic interlayer planarizing layer 135 may beinspected optically after is adhered to the hard mask layer 112, whereoptical inspection data may be obtained for the organic interlayerplanarizing layer 135, without obtaining data from the substrate 100 andlayers therein. Examples of suitable materials for the organicplanarizing layer include JSR NFC series, HM series, or Shin Etsu ODLseries. Specific examples include JSR NFC-1400, HM8005, Shin EtsuODL-30, ODL-50, and ODL-63.

As illustrated in FIG. 1D, the radiation sensitive resist layer 150 maybe patternwise exposed and developed as described above, where portions155 of the radiation sensitive resist layer 150 may be removed duringdeveloping to leave a relief pattern in the radiation sensitive resistlayer 150. The radiation sensitive resist layer 150 may be inspectedoptically for defects as described above.

FIG. 1E is an illustration of the substrate in FIG. 1D, after etching atrench 160 and stripping away the radiation sensitive resist layer 150,the antireflective coating 145, the low temperature oxide coating 140,and the organic interlayer planarizing layer 135. The presence of theoptical blocking layer 105 may allow for optical inspection of thepattern of the trench 160. The optical blocking layer 105 may be removedby a process such as chemical mechanical polishing (CMP), etching, etc.FIG. 1F is an illustration of the substrate 100 in FIG. 1E after removalof the optical blocking layer 105 and hard mask layer 112, to leave asubstrate 100 having the formation 165 created from the via 130 of FIG.1C and the trench 160 of FIG. 1E.

The optical blocking layer 105 described above for the examplesillustrated in FIGS. 1E-1F may alternatively be an optical absorbinglayer, wherein the optical absorbing layer may be configured tosubstantially absorb a range of wavelengths of light used in an opticalinspection technique. For example, as with the optical blocking layerdescribed above, an optical absorbing layer may be adhered directly to asubstrate (such as a semiconductor process wafer), and at least onelayer may be applied over the optical absorbing layer, where a firstlayer of the at least one layer may be adhered directly onto the opticalabsorbing layer. At least one inspection area of the substrate may beinspected optically at least one wavelength within the range of absorbedwavelengths, where the optical absorbing layer may extend substantiallythroughout the inspection area.

The optical absorbing layer may be configured to substantially absorblight at inspection wavelengths and thus prevent inspection data frombeing retrieved from light reflecting of layers below the opticalabsorbing layer which may not be of interest. For example, the opticalabsorbing layer may be configured to absorb greater than about 95% oflight of at least one wavelength, such as the inspection wavelength,within a range of absorbing wavelengths. In one embodiment the opticalabsorbing layer may have an imaginary index of refraction (k) betweenabout 0.1 and about 0.8 for light having a wavelength in a range fromabout 193 nanometers (nm) to about 260 nm. For example, the opticalabsorbing layer may have an imaginary index of refraction of 0.8 forlight having a wavelength of about 193 nm, where an optical inspectionlight may utilize single-wavelength light at about 193 nm, such as maybe generated by laser-based optical inspection system. In anotherembodiment, the optical absorbing layer may have an imaginary index ofrefraction (k) greater than about 0.2 for light having a wavelength in arange from about 260 nanometers to about 360 nanometers. In anotherembodiment, the optical absorbing layer may have an imaginary index ofrefraction less than about 0.1 for light having a wavelength greaterthan 450 nanometers. In one embodiment the optical absorbing layer mayhave a thickness from about 10 nanometers to 2000 nanometers, such asfrom about 80 nanometers to about 500 nanometers.

The optical absorbing layer may comprise an organic compound. In oneembodiment the organic compound may have a composition having at least70% carbon by weight. In another embodiment, the organic compound mayhave a molecular weight in a range from about 2,000 to about 25,000grams/mole. The organic compound may be a polymer. The organic compoundmay comprise, for example, a porphyrin, a phthalocyanine, tartrazine,phenolic polymer, polyhydroxystyrene-based polymer, derivatives thereof,or combinations thereof. It will be recognized that there exist numerousorganic compounds having sufficient absorption characteristics atinspection wavelengths and that the examples here are merelyillustrative of all such compounds which are included within embodimentsof the present invention.

FIG. 2 is a flow chart of steps in an inspection method utilizing anoptical blocking layer. In step 200, an optical blocking layer may beadhered to a substrate, such as a process wafer used in semiconductormanufacturing, for example. The optical blocking layer may be asdescribed above and may be adhered directly onto and in directmechanical contact with the substrate. The optical blocking layer may besubstantially opaque to a range of wavelengths of light.

In step 205, at least one layer is applied over the optical blockinglayer adhered to the substrate in step 200, where a first layer of theat least one layer may be adhered directly onto the optical blockinglayer. The at least one layer may comprise a hard mask layer, anantireflective coating (ARC) such as BARC (bottom antireflectivecoating), a radiation sensitive resist layer such as a photoresist, anoxide layer, a metal layer, a metal oxide layer, a nitride layer, adielectric layer, the like, or combinations thereof. For example, thefirst layer of the at least one layer may comprise a hard mask layer,where an antireflective coating may be adhered directly onto the hardmask layer, and a radiation sensitive resist layer may be adhereddirectly onto the antireflective coating layer, such as the exampleillustrated in FIG. 1A.

In step 210, at least one inspection area of the at least one layer maybe inspected optically at least one wavelength within the range ofwavelengths in which the optical blocking layer is substantially opaque.The optical blocking layer may extend substantially throughout theinspection area.

In step 235, the radiation sensitive resist layer may be patternwiseimaged, where a radiation or particle beam source may project radiationor energetic particles through a patterned mask onto the radiationsensitive resist layer. The mask may have a pattern of masked sectionswhich may be substantially opaque to the radiation or impenetrable tothe energetic particles, and unmasked sections which may besubstantially transparent to the radiation or penetrable to theenergetic particles. Radiation (such as ultra violet, deep ultra violet,extreme ultraviolet, x-rays, etc.) or particles (such as electron beam,ion beam, etc.) passing through the unmasked sections may be transmittedto the film to be absorbed in the exposed regions of the radiationsensitive resist layer. In one embodiment, the radiation or particlesmay induce the production of an acid catalyst in the exposed regions ofthe radiation sensitive resist layer, where unexposed regions may notproduce an acid catalyst, and wherein exposure to the radiation orenergetic particles may render the exposed regions soluble in adeveloper. In another embodiment, the radiation or particles may inducethe production of a base catalyst in the exposed regions of theradiation sensitive resist layer, and wherein exposure to the radiationor energetic particles may render the exposed regions soluble in adeveloper.

In step 240, the radiation sensitive resist layer may be developed in anappropriate developer, where soluble regions of the radiation sensitiveresist layer may be removed, leaving a relief pattern from the radiationsensitive resist layer remaining, such as the example illustrated inFIG. 1B. The developer may be an organic or aqueous based developer,such as an alkaline aqueous developer, such as tetrmethylammoniumhydroxide, for example. After developing in step 240, the process mayreturn to step 210 where the relief pattern may be inspected opticallyas described above.

The example of pattern-wise imaging the radiation sensitive resist layerin step 235 and step 240 is not meant to limit the scope of the presentinvention with regarding to producing a relief pattern which may beinspected as described herein. For example, the relief pattern may beproduced by such processes as imprint lithography to produce a reliefpattern on the surface of a layer substrate.

In step 215, optical inspection data may be obtained from the opticalinspection of step 210. Inspection data may comprise scanned imageinformation of the inspection area in comparison to image informationfor a known standard of the same pattern, such as that of a defect freesample or adjacent reference die. Such an inspection may be performedfor each step of a process depositing, removing, or modifying layers onthe substrate.

In step 220 a defect may be identified in at least one layer based onthe optical inspection data obtained in step 215. Based on inspectingthe at least one layer, a user may ascertain whether a defect is presentin the inspected layer (such as in a radiation sensitive layer, forexample) by comparison with a known standard. Such defects may includerandom or systematic defects such as bridging between surface features,missing features, etc.

In step 225, a step of a manufacturing process may be identified ashaving caused the defect identified in step 220. For example, thesubstrate may be a process wafer and the at least one layer may beapplied to the blocking layer in a semiconductor manufacturing process.For example, the defect in the sample may be caused by damage or adefect in the mask used during exposure of the radiation sensitiveresist layer. In another example, the defect may be caused by incorrectprocess conditions in the steps taken for adhering or etching the atleast one layer over the optical blocking layer.

In step 230, in response to identifying the manufacturing step in step225 which caused the defect, the manufacturing step may be modified toprevent the defect from recurring in the process. For example, a damagedor defective mask may be repaired or replaced, or process conditions maybe adjusted and new process tolerances may be implemented to reduce thechance of defect recurrence.

In step 245, the optical blocking layer may be removed, such as bychemical mechanical polishing, reactive ion removal or wet chemicalstripping, for example.

FIG. 3 is a flow chart of steps in an inspection method utilizing anoptical absorbing layer. In step 300, an optical absorbing layer may beadhered to a substrate, such as a process wafer used in semiconductormanufacturing, for example. The optical absorbing layer may be asdescribed above and may be adhered directly onto and in directmechanical contact with the substrate. The optical absorbing layer maybe configured to substantially absorb a range of wavelengths of light.

In step 305, at least one layer is applied over the optical absorbinglayer adhered to the substrate in step 300, where a first layer of theat least one layer may be adhered directly onto the optical absorbinglayer. The at least one layer may comprise a hard mask layer, anantireflective coating (ARC) such as BARC, a radiation sensitive resistlayer such as a photoresist, an oxide layer, a metal layer, a metaloxide layer, a nitride layer, a dielectric layer, the like, orcombinations thereof. For example, the first layer of the at least onelayer may comprise a hard mask layer, where an antireflective coatingmay be adhered directly onto the hard mask layer, and a radiationsensitive resist layer may be adhered directly onto the antireflectivecoating layer.

In step 310, at least one inspection area of the at least one layer maybe inspected optically at least one wavelength within the range ofwavelengths in which the optical absorbing layer is configured tosubstantially absorb. The optical absorbing layer may extendsubstantially throughout the inspection area.

In step 335, the radiation sensitive resist layer may be patternwiseimaged, where a radiation or particle beam source may project radiationor energetic particles through a patterned mask onto the radiationsensitive resist layer. The mask may have a pattern of masked sectionswhich may be substantially opaque to the radiation or impenetrable tothe energetic particles, and unmasked sections which may besubstantially transparent to the radiation or penetrable to theenergetic particles. Radiation (such as ultra violet, deep ultra violet,extreme ultraviolet, x-rays, etc.) or particles (such as electron beam,ion beam, etc.) passing through the unmasked sections may be transmittedto the film to be absorbed in the exposed regions of the radiationsensitive resist layer. In one embodiment, the radiation or particlesmay induce the production of an acid catalyst in the exposed regions ofthe radiation sensitive resist layer, where unexposed regions may notproduce an acid catalyst, and wherein exposure to the radiation orenergetic particles may render the exposed regions soluble in adeveloper. In another embodiment, the radiation or particles may inducethe production of a base catalyst in the exposed regions of theradiation sensitive resist layer, and wherein exposure to the radiationor energetic particles may render the exposed regions soluble in adeveloper.

In step 340, the radiation sensitive resist layer may be developed in anappropriate developer, where soluble regions of the radiation sensitiveresist layer may be removed, leaving a relief pattern from the radiationsensitive resist layer remaining. The developer may be an organic oraqueous based developer, such as an alkaline aqueous developer, such astetrmethylammonium hydroxide, for example. After developing in step 340,the process may return to step 310 where the relief pattern may beinspected optically as described above.

In step 315, optical inspection data may be obtained from the opticalinspection of step 310. Inspection data may comprise scanned imageinformation of the inspection area in comparison to image informationfor a known standard of the same pattern, such as that of a defect freesample. Such an inspection may be performed for each step of a processdepositing, removing, or modifying layers on the substrate.

In step 320 a defect may be identified in at least one layer based onthe optical inspection data obtained in step 315. Based on inspectingthe at least one layer, a user may ascertain whether a defect is presentin the inspected layer (such as in a radiation sensitive layer, forexample) by comparison with a known standard. Such defects may includerandom or systematic defects such as bridging between surface features,missing features, etc.

In step 325, a step of a manufacturing process may be identified ashaving caused the defect identified in step 320. For example, thesubstrate may be a process wafer and the at least one layer may beapplied to the blocking layer in a semiconductor manufacturing process.For example, the defect in the sample may be caused by damage or adefect in the mask used during exposure of the radiation sensitiveresist layer. In another example, the defect may be caused by incorrectprocess conditions in the steps taken for adhering or etching the atleast one layer over the optical absorbing layer.

In step 330, in response to identifying the manufacturing step in step325 which caused the defect, the manufacturing step may be modified toprevent the defect from recurring in the process. For example, a damagedor defective mask may be repaired or replaced, or process conditions maybe adjusted and new process tolerances may be implemented to reduce thechance of defect recurrence.

In step 345, the optical blocking layer may be removed, such as bychemical mechanical polishing, for example.

The foregoing description of the embodiments of this invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and obviously, many modifications and variations arepossible. Such modifications and variations that may be apparent to aperson skilled in the art are intended to be included within the scopeof this invention as defined by the accompanying claims.

1. An inspection method, said method comprising: adhering an opticalblocking layer directly onto and in direct mechanical contact with asemiconductor process wafer, said optical blocking layer beingsubstantially opaque to a range of wavelengths of light; applying atleast one layer over said optical blocking layer, wherein a first layerof said at least one layer is adhered directly onto said opticalblocking layer; and inspecting optically at least one wavelength withinsaid range of wavelengths at least one inspection area of said at leastone layer, said optical blocking layer extending substantiallythroughout said inspection area.
 2. The method of claim 1, wherein saidat least one inspection area has topographical variation.
 3. The methodof claim 1, wherein said first layer of said at least one layer is ahard mask layer, said applying at least one layer over said opticalblocking layer comprising adhering an antireflective coating directlyonto said hard mask layer.
 4. The method of claim 3, wherein saidapplying at least one layer over said optical blocking layer furthercomprises: adhering a radiation sensitive resist layer directly ontosaid antireflective coating layer.
 5. The method of claim 4, furthercomprising: before said inspecting optically, patternwise imaging saidradiation sensitive resist layer through a mask, exposing at least oneregion of said radiation sensitive resist layer to radiation, resultingin production of an acid catalyst in said exposed at least one region ofsaid radiation sensitive resist layer; and developing said exposed atleast one region, resulting in removal of regions of said radiationsensitive resist layer, wherein a relief pattern from said radiationsensitive resist layer remains following said removal.
 6. The method ofclaim 1, said method further comprising: obtaining optical inspectiondata from said inspecting; and identifying based on said opticalinspection data a defect in said at least one layer.
 7. The method ofclaim 6, wherein said at least one layer is applied to said opticalblocking layer in a semiconductor manufacturing process, said methodfurther comprising: identifying a step in said semiconductormanufacturing process having caused said defect; and responsive to saididentifying said step, modifying said step in said semiconductormanufacturing process to prevent said defect.
 8. The method of claim 1,further comprising removing said optical blocking layer after saidinspecting.
 9. The method of claim 1, wherein said optical blockinglayer comprises a material selected from the group consisting oftantalum nitride, tungsten nitride, gallium nitride, titanium nitride,tantalum, titanium, hafnium oxide, and combinations thereof.
 10. Aprocess wafer optical inspection method, said method comprising:adhering an optical absorbing layer to a semiconductor process wafer,said optical absorbing layer configured to substantially absorb a rangeof wavelengths of light; applying at least one layer over said opticalabsorbing layer, wherein a first layer of said at least one layer isadhered directly onto said optical absorbing layer; and inspectingoptically at least one wavelength within said range of wavelengths atleast one inspection area of said process wafer having said opticalabsorbing layer, said optical absorbing layer extending substantiallythroughout said inspection area.
 11. The method of claim 10, whereinsaid optical absorbing layer comprises an organic compound.
 12. Themethod of claim 11, wherein said organic compound has a compositionhaving at least 70% carbon by weight.
 13. The method of claim 11,wherein said optical absorbing layer further comprises a siliconantireflective coating.
 14. The method of claim 10, wherein said opticalabsorbing layer is configured to absorb greater than about 95% of lightof at least one wavelength within said range of wavelengths.
 15. Themethod of claim 10, wherein said optical absorbing layer has animaginary index of refraction (k) between about 0.1 and about 0.8 forlight having a wavelength in a range from about 193 nanometers to about260 nanometers.
 16. The method of claim 10, wherein said opticalabsorbing layer has an imaginary index of refraction (k) greater thanabout 0.2 for light having a wavelength in a range from about 260nanometers to about 360 nanometers.
 17. The method of claim 10, whereinsaid optical absorbing layer has an imaginary index of refraction (k)less than about 0.1 for light having a wavelength greater than 450nanometers.
 18. A manufacturing method, comprising: providing anintegrated semiconductor wafer having an optical blocking layer, saidblocking layer configured to block a range of wavelengths of light;adhering a photoresist layer to said wafer having said blocking layer,wherein said adhering has resulted from a semiconductor manufacturingprocess; inspecting optically at least one wavelength within said rangeof wavelengths at least one inspection area of said photoresist layer,said optical blocking layer extending substantially throughout saidinspection area; based on said inspecting, ascertaining if a defect ispresent within said photoresist layer; and changing said semiconductormanufacturing process to prevent said defect, if said defect is presentwithin said photoresist layer.
 19. The method of claim 18, furthercomprising: etching said wafer having said photoresist layer utilizingan etching step of a semiconductor manufacturing process, wherein atleast one portion of said photoresist layer is removed by said etching;after said etching, inspecting optically at least one wavelength withinsaid range of wavelengths at least one inspection area of said wafer,said optical blocking layer extending substantially throughout saidinspection area; based on said inspecting said at least one inspectionarea of said wafer, ascertaining that a defect is present on said wafer;based on said ascertaining, changing said etching step of saidsemiconductor manufacturing process if said defect is present on saidwafer; and removing said optical blocking layer from said wafer.
 20. Themethod of claim 18, wherein said optical blocking layer comprises amaterial selected from the group consisting of tantalum nitride,tungsten nitride, gallium nitride, titanium nitride, tantalum, titanium,hafnium oxide, and combinations thereof.